I would like to propose a major runway capacity improvement for Heathrow Airport. This would involve building two new parallel 12000' runways, within the existing Northern and Southern runways, separated by just 30m. The idea is that lengthy planning and public consultation would not be required, as the flight path arrangements would not change significantly from those of today. This avoids another No Third Runway campaign by the environmentalists.
The two new parallel runways would reduce the huge pressure on the existing runways at Heathrow, by allowing staggered parallel operations and steeper approaches for smaller aircraft. Landing aircraft would be directed to the closest runway to their stand. Lengthy holding around London would no longer be required, even in bad weather. Typical operational capacity would fall from 98%, to just over 60% when completed.
In preparation, all groundworks would be done at night when the airport is closed, or by cut and cover tunnelling alongside the active runways. The new runways would be constructed off-site, near the M25. They would be built in prefabricated and completed sections (75m x 75m), then moved on rails into position on tracks, buried alongside the existing runways. No airfield construction work would be carried out above ground level, so air operations can continue during runway section movements. In effect, the new runways will appear longer each day until completed. Each finished runway could open to air traffic within a matter of months. Completion of both new runways would be done by April 2015. The construction cost would be in the region of £500m.
During peak periods, aircraft would land on the new inner runways, so vacating the active runway would not conflict with departures using one or both of the existing outer runways. All Terminal 4 operations would use the Southern outer runway for the same reason. All departing aircraft would use the nearest outer runway from their stand. Most active runway crossing would be done via the undershoot areas to the far east or west of the airfield. Aircraft having to cross an active runway would be virtually elimated.
All operations would be staggered, so avoiding wingtip incidents on the extremely close parallel runways. Current long taxi distances and queues to and from the runway / stands would be greatly reduced.
The two new inner runways would be marked and configured for both full length 12000' operation and 7500' operation, with the threshold displaced at both ends for the shorter runway. The new inner runways would offer dual 3 degree and 6 degree glideslope for both easterly and westerly approaches.
As stacking over London would reduce the present 6000' restriction on departure would no longer be needed. This enables aircraft to climb on runway heading for longer, reducing the conflict of aircraft turning across the path of the northern or southern runways respectively.
[Edited 2012-03-28 07:07:35]